Oil is present in the compressed gases downstream of Oil-Flooded Screw or Lubricated. Reciprocating Compressors. To improve compressor efficiency, this oil must be removed to finite levels. This is possible only by the use of successive stages of coalescing oil separators followed by charcoal adsorber. Typically for 10ppbw or less oil carry-over limit, three stages of coalescing, followed by a charcoal adsorber is required. Coalescing separators remove the oil droplets; whereas the charcoal adsorbers remove the vapor phase oil. Special Micron Filters are employed downstream of adsorbers to catch particulates from the charcoal.